1. Field of the Invention
The present invention relates to interpolymers of vinyl acetate and their use as textile sizes. More particularly, it relates to acid modified interpolymers of vinyl acetate containing 2-acrylamido-2-methylpropanesulfonic acid and to textiles, especially spun polyester textiles, sized with these interpolymers.
2. Description of the Prior Art
In conventional loom operations, yarn is sized with an aqueous solution of a water-soluble material woven into cloth on a conventional loom with a mechanical shuttle and then the size is removed in a water bath. Many water-soluble compositions are used as textile sizes, for example, poly(vinyl alcohols), carboxymethyl cellulose, starch, styrene-maleic anhydride copolymers, acrylic copolymers and vinyl acetate copolymers. While these sizes have been adequate for natural textile fibers and for many of the synthetic textile fibers, they exhibit deficiencies in the sizing of yarns of spun polyester and spun polyester blended with natural fibers. Poly(vinyl alcohols) lack ease of removability from the sized yarn and are difficult to recover or eliminate from the waste stream. Carboxymethyl cellulose is low in sizing efficiency and difficult to recover from the waste stream. Starch is similar to carboxymethyl cellulose in sizing efficiency and recoverability and is a stronger pollutant because it has a high biochemical oxygen demand. Styrene-maleic anhydride copolymers are deficient in adhesion to spun polyester, being easily shed, leaving the textile fiber unprotected. Acrylic copolymer sizes have good adhesion but are deficient in strength and low in efficiency. Vinyl acetate copolymers are, in general, low in efficiency, and lack ease of removability from the sized yarn.
U.S. Pat. No. 3,919,449 discloses acid-modified poly(vinyl acetate) textile sizes and textiles sized therewith. The sizes comprise interpolymers of 90.5 to 95.5 percent by weight vinyl acetate, 4.0 to 7.5 percent by weight acrylic acid and 0.5 to 2.0 percent by weight of a monoalkyl ester of maleic, fumaric, or citraconic acids. They are used for sizing spun polyester and spun blends of polyester and natural fibers.
The latex interpolymers of U.S. Pat. No. 3,919,449 are prepared by redox polymerization with a two component initiator system in the temperature range of 40.degree. to 60.degree. C. and more preferably, at a temperature in the range of 40.degree. to 45.degree. C. in order to produce interpolymers of sufficient molecular weight to provide adequate strength to the polymer. While these latex interpolymers provide a considerable improvement over prior art interpolymers of vinyl acetate in adhesion to spun polyester yarn and in ease of removability, a need exists for a further improvement in ease of removability. Furthermore, the process of interpolymerization while it is characterized by a low degree of coagulum, can be troublesome in commercial production because of the difficulty of controlling the polymerization at the relatively low temperatures in the range of 40.degree. to 60.degree. C. and because the coagulum can cause filtering problems and kettle fouling.